#region Copyright & License

//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#endregion

// .NET Compact Framework 1.0 has no support for reading assembly attributes
#if !NETCF

using System;
using log4net.Core;
using log4net.Plugin;
using log4net.Util;

namespace log4net.Config {
  /// <summary>
  /// Assembly level attribute that specifies a plugin to attach to 
  /// the repository.
  /// </summary>
  /// <remarks>
  /// <para>
  /// Specifies the type of a plugin to create and attach to the
  /// assembly's repository. The plugin type must implement the
  /// <see cref="IPlugin"/> interface.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true)]
  [Serializable]
  public sealed class PluginAttribute : Attribute, IPluginFactory {
    #region Public Instance Constructors

    /// <summary>
    /// Initializes a new instance of the <see cref="PluginAttribute" /> class
    /// with the specified type.
    /// </summary>
    /// <param name="typeName">The type name of plugin to create.</param>
    /// <remarks>
    /// <para>
    /// Create the attribute with the plugin type specified.
    /// </para>
    /// <para>
    /// Where possible use the constructor that takes a <see cref="System.Type"/>.
    /// </para>
    /// </remarks>
    public PluginAttribute(string typeName) {
      m_typeName = typeName;
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="PluginAttribute" /> class
    /// with the specified type.
    /// </summary>
    /// <param name="type">The type of plugin to create.</param>
    /// <remarks>
    /// <para>
    /// Create the attribute with the plugin type specified.
    /// </para>
    /// </remarks>
    public PluginAttribute(Type type) {
      m_type = type;
    }

    #endregion Public Instance Constructors

    #region Public Instance Properties

    /// <summary>
    /// Gets or sets the type for the plugin.
    /// </summary>
    /// <value>
    /// The type for the plugin.
    /// </value>
    /// <remarks>
    /// <para>
    /// The type for the plugin.
    /// </para>
    /// </remarks>
    public Type Type {
      get { return m_type; }
      set { m_type = value; }
    }

    /// <summary>
    /// Gets or sets the type name for the plugin.
    /// </summary>
    /// <value>
    /// The type name for the plugin.
    /// </value>
    /// <remarks>
    /// <para>
    /// The type name for the plugin.
    /// </para>
    /// <para>
    /// Where possible use the <see cref="Type"/> property instead.
    /// </para>
    /// </remarks>
    public string TypeName {
      get { return m_typeName; }
      set { m_typeName = value; }
    }

    #endregion Public Instance Properties

    #region Implementation of IPluginFactory

    /// <summary>
    /// Creates the plugin object defined by this attribute.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Creates the instance of the <see cref="IPlugin"/> object as 
    /// specified by this attribute.
    /// </para>
    /// </remarks>
    /// <returns>The plugin object.</returns>
    public IPlugin CreatePlugin() {
      Type pluginType = m_type;
      if (m_type == null) // Get the plugin object type from the string type name
        pluginType = SystemInfo.GetTypeFromString(m_typeName, true, true);

      // Check that the type is a plugin
      if (!(typeof (IPlugin).IsAssignableFrom(pluginType)))
        throw new LogException("Plugin type [" + pluginType.FullName +
                               "] does not implement the log4net.IPlugin interface");

      // Create an instance of the plugin using the default constructor
      var plugin = (IPlugin) Activator.CreateInstance(pluginType);

      return plugin;
    }

    #endregion Implementation of IPluginFactory

    #region Override implementation of Object

    /// <summary>
    /// Returns a representation of the properties of this object.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Overrides base class <see cref="Object.ToString()" /> method to 
    /// return a representation of the properties of this object.
    /// </para>
    /// </remarks>
    /// <returns>A representation of the properties of this object</returns>
    public override string ToString() {
      if (m_type != null)
        return "PluginAttribute[Type=" + m_type.FullName + "]";
      return "PluginAttribute[Type=" + m_typeName + "]";
    }

    #endregion Override implementation of Object

    #region Private Instance Fields

    Type m_type;
    string m_typeName;

    #endregion Private Instance Fields
  }
}

#endif // !NETCF